When a television, a video, a DVD (Digital Versatile Disk) recorder, audio equipment, and the like, are purchased and installed at home, input/output terminals are mutually connected and wired by using a copper wire or optical fiber cable. Recently, however, the number of devices capable of being mutually connected at home has increased and simultaneously, wiring to be carried out has become very complicated due to high performance of devices. As a result, it has been very difficult for a general user to connect and wire devices. In addition, a large number of various new standards for connection cables have appeared, and a user must pay for such connection cables.
Since devices such as flat television have achieved light weight, demands for freely carrying a device to a room where a user wants to use it have increased in general. However, if wiring is complicated, such movement cannot be carried out easily.
As a method for dissolving such problems, devices capable of wiring communication therebetween have been proposed. An example of a developed device includes a television which is divided into two housings, i.e., a liquid display unit and a tuner unit, and in which wireless communication is carried out between the two housings. As such a wireless communication technology, for example, wireless LAN (Local Area Network), such as standardized IEEE802.11g used for wireless communication of PC (Personal Computer), has been used. When devices are connected wirelessly, it is not necessary to carry out physical connection in which connection cables are inserted into devices. Furthermore, it is not necessary to purchase connection cables.
Furthermore, Japanese Patent Unexamined Publication No. 2004-235960 discloses a method of periodically trying to detect the presence of devices when a plurality of devices are mutually connected, in which the detection efficiency is improved by relatively increasing the period of detection when the presence of the device cannot be detected.
Furthermore, Japanese Patent Unexamined Publication No. 2004-015558 discloses a method in which when devices are connected mutually, devices are allowed to be physically close and releasing radio wave is relatively weakened so as to limit the arrival range of radio wave to a physically close area, thereby preventing devices that should not be connected from being detected.
Herein, a system including devices connected mutually by using a wireless LAN technology is described with reference to drawings.
FIG. 5 is a diagram showing a configuration of a system of a conventional communication connection device. This system includes communication connection device 510, display device 120b, communication connection device 530, and communication connection device 540. In FIG. 5, communication connection device 510, communication connection device 530 and communication connection device 540 are mutually detectable by wireless communication. Furthermore, to communication connection device 510, display device 120b for displaying to a user is connected. Hereinafter, each device is described.
Communication connection device 510 includes input unit 111b, UI (User Interface) control unit 511, communication unit 113b, device ID 1131b, existence notification detection unit 114b, contents reproduction unit 115b, and drawing unit 116b. 
Input unit 111b is an input device to which a physical operation request by a user is input. Input unit 111b is a remote controller and a light receiver using infrared rays, a physical switch built in communication connection device 510, or a pointing device such as a mouse.
UI control unit 511 receives input from input unit 111b, existence notification detection unit 114b and communication unit 113b, and outputs information to be displayed on a screen to drawing unit 116b, and thereby manages state transition of entire communication connection device 510. In particular, by changing a screen to be displayed on display device 120b in accordance with the input from input unit 111b, GUI (Graphic User Interface) is realized.
UI control unit 511 is a built-in computer for controlling, which includes a CPU (Central Processing Unit) and a semiconductor memory for storing and executing a computer program that determines an operation of the CPU. Specific operation of UI control unit 511 is described later with reference to a flowchart shown in FIG. 6.
Communication unit 113b is mutually connected to another communication unit built in another communication connection device, thereby carrying out two-way communication. Communication unit 113b is, for example, an LSI (Large Scale Integrated circuit) for realizing wireless LAN. Communication unit 113b holds device ID 1131b that is ID specific to each communication unit for distinguishing and identifying the communication unit from other communication units.
Device ID 1131b is a device ID stored in communication unit 113b. When communication unit 113b is LSI for wireless LAN, device ID 1131b is, for example, MAC (Media Access Control) address for distinguishing LAN connection devices all over the world.
Existence notification detection unit 114b performs broadcast communication to communication unit 113b with a wireless communication path. When another communication connection device receives a signal of broadcast communication, it detects the existence of communication connection device 510. Furthermore, when existence notification detection unit 114b receives a signal of broadcast communication released by another communication connection device, it can detect the existence of the other communication connection device. Protocol for notifying and detecting the existence of a device in this way is defined by specification of IEEE802.11b.
Contents reproduction unit 115b receives contents that have been received by communication unit 113b, and reproduces and outputs them to drawing unit 116b in accordance with the control by UI control unit 511. Herein, contents include information such as picture, music, and Web page, which a user views via display device 120b. When contents reproduction unit 115b may be MPEG (Motion Picture Expert Group)-2 video decoder when the contents are MPEG-2 video.
Drawing unit 116b receives an input of information for drawing contents output by contents reproduction unit 115b and information for drawing a screen of GUI output by UI control unit 511, generates display information of a screen by synthesizing the above-mentioned information, converts the display information into a signal format that can be input to display device 120b, and outputs it. Drawing unit 116b is a drawing LSI such as a graphic accelerator.
Next, display device 120b is described. Display device 120b receives the output from communication connection device 510, converts it into a physical phenomenon such as screen display or sound which a user can perceive, and presents it to a user. Display device 120b is, for example, a graphics display such as LCD (Liquid Crystal Display) and a speaker.
Then, communication connection device 530 is described. Communication connection device 530 includes input unit 111c, UI control unit 131b, communication unit 113c, device ID 1131c, existence notification detection unit 114c, and contents storage unit 132c. 
UI control unit 131b controls state transition of entire communication connection device 530. Contents storage unit 132c stores contents and outputs them to communication unit 113c in accordance with the request from UI control unit 131b. When reproduction of contents is instructed by input unit 111c, UI control unit 131b recognizes this instruction and issues a command to contents storage unit 132c to output contents to communication unit 113c. With this command, contents are input to another communication connection device 510 via communication unit 113c. Thus, the output contents are displayed on display device 120b by way of communication unit 113b, contents reproduction unit 115b, and drawing unit 116b of communication connection device 510.
Next, communication connection device 540 is described. Communication connection device 540 has the same configuration as that of communication connection device 530. However, value of the device ID stored in each communication unit is different from each other, so that communication is carried out in a state in which two communication connection devices can be distinguished from each other.
Next, connection processing by communication connection device 510 is described. Herein, the connection processing is a processing for detecting what device is present as a communication connection device existing within the range in which radio wave can reach.
FIG. 6 is a flowchart showing a connection processing in a conventional communication connection device. FIGS. 7A and 7B are views showing a displayed screen of a conventional communication connection device. Hereinafter, the flow of processing is described in the order shown in steps in FIG. 6.
[1] Existence notification detection unit 114b analyzes information received by communication unit 113b and detects one or a plurality of detectable communication connection devices. Then, existence notification detection unit 114b passes a list of detected devices to UI control unit 511 (S201a).
[2] UI control unit 511 issues a command to drawing unit 116b to display the list of the detected devices on a screen. Drawing unit 116b allows display device 120b to display the list of the detected devices on a screen (S601).
[3] UI control unit 511 allows a display for prompting a user to select a device to be connected from the displayed list of detected devices on a screen. Screen 710 in FIG. 7A shows an example of a screen image displayed in step S601. Screen 710 shows that four devices are detected according to list 711. Furthermore, in information on the screen, a message for prompting a user to input selection is displayed (S602).
[4] A user selects a device to be connected from the detected devices displayed in step S602. This operation is executed when a user operates input unit 111b and thereby UI control unit 511 grasps what device is selected. For example, in screen 710, selection is carried out by moving box cursor 712 to a desired communication connection device and determining it (S603).
[5] To the device selected in step S603, communication connection device 510 is connected. This operation is carried out when UI control unit 511 commands so that communication unit 113b is connected to the device selected by UI control unit 511 in step S602 (S604).
[6] UI control unit 511 allows display device 120b to display the completion of connection. For example, screen 720 in FIG. 7B displays that a DVD recorder is connected (S605).
The merit of wireless communication is that physical connection is not necessary as mentioned above. However, there is a demerit that devices that are present in the vicinity may be detected mistakenly. For example, when a device of another house in a condominium is located at the reverse side of the wall of the user's device, since the physical distance is small, the device may be detected mistakenly.
If the device of another house is detected mistakenly, the device is mistaken as the user's device and connected thereto. On the contrary, the user's device may be used by another user of another house. Alternatively, there is a problem of privacy that a user of one house knows what kind of devices is used in other houses.
A method for avoiding detection error, according to a standard of wireless LAN, includes a method of registering a network name common to all the devices to be connected. In this case, only devices having the same network name as the registered network name are detected.
However, inputting the network name into respective devices is complicated unless a sufficient input/output device is provided. Furthermore, when an operator inputs the network name, even if only one letter is typed mistakenly, connection cannot be carried out. The inputting is a stressful and complicated procedure.